1. Field of the Invention
The present invention relates to a hardness tester and a hardness testing method.
2. Description of Related Art
Conventionally, for each kind of hardness tester, such as a Brinell hardness tester, a Vickers hardness tester, a Knoop hardness tester, and the like, hardness of a specimen has been measured based on dimensions of an indentation formed in a surface of the specimen. For example, in the Vickers hardness tester, an indenter with a four-sided pyramid-shaped tip is pressed onto a surface of the specimen, then the length of diagonal lines in the indentation formed on the specimen is measured with an optical microscope and the like. Then, based on the measured length of the diagonal lines in the indentation, hardness is calculated. Also, in order not to generate measurement errors in measuring the dimensions of the indentation, a user must perform focusing on the surface of the specimen on which the indentation has been formed.
A known example for the hardness tester in which focusing is performed designates a plurality of focus adjustment positions on the specimen on which the indentation has been formed. An image capturer is then operated so as to focus on the designated focus adjustment positions and an image of the indentation is captured. A degree of focus for the indentation in the designated focus adjustment position is calculated, then displayed on a monitor. Focus adjustment can thus be performed favorably (see, for example, Japanese Patent Laid-open Publication No. 2011-2247).
In the conventional hardness tester, during programming of a test position, a broad range image of a specimen S must be obtained in order to verify at which location on the specimen S the hardness test will be performed. For example, as shown in FIG. 6, by combining a plurality of images A1-A9 captured by displacing the specimen S in a horizontal direction, a broad range image G1 is obtained. Then, the broad range image G1 obtained is used to perform hardness testing.
Herein, a process after the broad range image G1 is obtained in the conventional hardness tester is described with reference to the flowchart of FIG. 8 and to the schematic diagram of FIG. 9 illustrating a tester main body 20 of a hardness tester. First, a test pattern is set with respect to the obtained broad range image G1 (step S101). Herein, the setting of a test pattern refers to setting test conditions, a test start point, number of rows and columns, pitch, and the like. By setting the test pattern, as shown in FIG. 6, programming of test positions P1, P2, . . . is performed.
When the test pattern has been set, the hardness test begins automatically. The specimen S (specimen stage 2) is displaced so as to position the predetermined test positions (in the first cycle, the test start point) that opposes an indenter 14a (step S102). An indentation is then created at the test position (step S103).
Next, whether or not indentations have been created for all of the programmed test positions is determined (step S104). When indentation has not been performed for all of the test positions (that is, when it is determined that at least one test position has not had an indentation created thereat) (step S104: NO), the process moves to step S102 and displaces the specimen S so as to position the next test position opposite the indenter 14a. Meanwhile, when indentation is determined to have been performed for all test positions (step S104: YES), the specimen S is displaced so as to position predetermined scanning positions (positions where indentation has been performed) opposite a field lens 15 used for indentation scanning (step S105). An autofocus process is then performed to focus on the scanning position (step S106).
When the autofocus process is performed, an indentation is scanned in the scanning position, then a hardness value for the specimen S is calculated based on the dimensions of the scanned indentation (step S107).
Finally, whether or not the indentation has been scanned in all scanning positions is determined (step S108). When the indentation has not been scanned in all scanning positions (that is, when it is determined that the indentation has not been scanned in at least one scanning position) (step S108: NO), the process moves to step S105 and displaces the specimen S so as to position the next scanning position opposite the indenter 14a. Meanwhile, when the indentation is determined to be scanned at all scanning positions (step S108: YES), the process ends.
In this way, the broad range image G1 is obtained and test positions are programmed using the obtained broad range image G1, thereby enabling a hardness test to be performed in the conventional hardness tester.